1. Technical Field
This invention relates to exercise machines, and more particularly to exercise machines having a turntable rotated reciprocally by the user.
2. Description of the Prior Art
Exercise machines having turntables which are reciprocally rotated by the user are known. One of may earlier patents, Rice U.S. Pat. No. 4,538,807, the disclosure of which is incorporated herein by reference, describes a torso building exercise machine having an inertial resistance. By this it is meant that the resistance experienced by the user in rotating the turntable is produced by the turntable's rotational moment of inertia. The largest portion of the work performed by the user occurs at the end of each rotation as the user slows and then reverses the turntable's rotation. In the middle of the stroke the turntable rotates substantially resistance free, producing what may be termed a "dead spot" during which the user experiences little resistance.
Other turntable exercise machines having other forms of resistance have been developed. Phillips et al. U.S. Pat. No. 3,702,188 discloses a rotatable exerciser having a linear, hydraulically produced resistance. The user stands on a pair of rotatable members, each of which drives a pair of hydraulic cylinders through rack and pinion means. As each foot receiving member is reciprocally rotated, the pistons of its hydraulic cylinders are alternately and oppositely extended and retracted. At any angle of rotation of the foot receiving member, the resistance is linearly related to the rate of such rotation, and independent of the turntable's angular position.
Simjian U.S. Pat. No. 3,784,193 discloses a turntable exercise device having a friction brake resistance. The resistance provided by the Simjian device is constant, being substantially independent of both the turntable's angular position from dead center and the rate of rotation of the turntable.
Mattox U.S. Pat. No. 4,249,725 discloses an exercise apparatus having a gear driven spinning rotor which rotates many times during each stroke by the user. Resistance is provided both by the inertia of the spinning rotor and by the drag through the air of radially mounted paddles on the rotor. Like the Phillips et al device, the resistance of the Mattox exerciser is linear, being dependent on the rate of rotation of the rotor but independent of its angular position.
The Phillips et al., Simjian and Mattox devices all provide the same resistance in either direction.